How to pass a variable from webview Javascsript to Xamarin Forms code?

Question

I'm having a webpage that takes some information from the user, process it on the server side PHP and then gets the response back from the server.

Now I need to implement this (Including the web UI) into my Xamarin Forms app, so I thought about having a webview that loads the URL of the webpage, but now I can't figure out (Not even with googling) how to get the Javscript's resultant variable's value back to C#.

Here is a Javascript sample:-

xhttp.onreadystatechange = function () {
    if (this.readyState == 4 && this.status == 200) {
      let data = JSON.stringify(JSON.parse(this.responseText));
      // Now I want to pass 'data' variable to C#
    }
};

The app should wait till it receives this variable's value then executes other things, or until the user presses the back button to cancel the whole thing...

Any help is appreciated, thanks in advance. ^_^

I can't really understand the documentation well. Maybe you can give example ? — Mohamed Ashraf
– Mohamed Ashraf, Commented Apr 22, 2020 at 15:24

ColeX · Accepted Answer · 2020-04-22 15:16:00Z

1

First , create custom renderer for webview .

Then , wrap the js function with native api on each platform and add it into webview .

Invoke the function and pass the data , the method will aslo trigger in the renderer .

Refer https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/custom-renderer/hybridwebview .

answered Apr 22, 2020 at 15:16

ColeX

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6 Comments

Mohamed Ashraf Over a year ago

The problem is that the webpage and javascript code is not local, I can't just wrap js code inside the Xamarin app itself, moreover, I can't really understand the documentation well. Maybe you can give example ?

ColeX Over a year ago

Check the sample link :learn.microsoft.com/en-us/samples/xamarin/xamarin-forms-samples/…

Mohamed Ashraf Over a year ago

I did check the sample link, but the same issue, it uses a local html page, on the other side, I want to load an external one, a url link...

Mohamed Ashraf Over a year ago

However, I modified the custom renderer to allow using external links, So I will count this as the answer ^_^ One more thing, how to add a window property, in JS I can say if(window.hasOwnProperty("uid")) { doSomething(uid); } but how to assign the uid itself when loading the url ?!

ColeX Over a year ago

do you mean how to pass the data when invoke the method ?

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